The invention pertains to an air mass flow sensor pipe and to a combustion engine, which comprises such an air mass flow sensor pipe.
Mass air flow sensors are used to determine the air intake flow to a combustion engine, for example an engine in a vehicle or for industrial or marine purposes. It is very important to have knowledge of the current mass flow value of an air intake duct to the combustion engine, since this value is used in various calculations and modellings, which are carried out by one or several electronic control devices in the vehicle. The electronic control device emits signals to the combustion engine, so that it is driven optimally with respect to performance and emitted emissions. The air flow sensor may, however, generate mass flow values, which must be adjusted due to sensor-dependent characteristics or unique conditions for the current use.
At the installation of an air flow sensor in a combustion engine system it is thus important that a calibration of the air flow sensor is carried out at the installation, so that correct measuring values of the air mass flow is delivered to the control device.
Currently, an adjustment process is also applied for air flow sensors which takes place while driving, e.g. in heavy goods vehicles such as trucks and buses. In industrial or marine uses of the engine, the circumstances are usually more specific, which may entail that each engine requires individual adjustment at calibration. The mass flow values which are generated by such an air flow sensor are adjusted based on a correction factor. This adjustment procedure may be carried out more or less frequently during the operation of the engine.
Different types of installations entail different requirements in relation to the air flow sensor with respect to capacity, silencing and available space. Thus, different types of components and concepts have been developed to assemble air flow sensors in combustion engines.
U.S. Pat. No. 4,624,134 relates to an air flow sensor for a combustion engine in a vehicle. An air flow sensor is placed inside a bypass duct in a curved pipe, which is connected between an air intake and the combustion engine. This construction entails increased measuring accuracy of the air mass flow.